This invention relates to improvements in and concerning a retaining device for cords. More particularly, this invention relates to a retaining device for cords, which device can be applied to cords of varying cross section such as twin-core cords and coaxial cords.
Grommets and retaining devices for cords are generally used on electric appliances for the purposes of preventing cords from being injured on their surfaces by sharp corners of holes perforated through panels where the cords connected to the appliance interiors are led out for external connection or for the purpose of preventing such cords from being ripped off the points of contact within the appliances by inadvertent pulls given to the portions of the cords outside the appliance housings.
The cord retaining devices of this type which are prevalent in the market are represented by that which is disclosed in Japanese Utility Model Laid-Open Publication No. 131595/1975 and that which is disclosed in U.S. Pat. No. 3,958,300 which has issued to the applicant of this patent application. For the purpose of preventing cords from being ripped off the points of contact within the appliances by dint of pulls externally given to the cords, these conventional cord retaining devices have been expected to fulfil the requirement that the paths formed therein for admitting cords should possess contours conforming to the cross sections of the cords to be laid therein.
In the former cord retaining device, a push piece is disposed in such a way that it will protrude into an otherwise smoothly continued path to be formed for admitting a cord therein by the two halved blocks of the device being folded over each other across a hinge piece and this protruding push piece will serve to pinch the cord in a zigzagging form so that any pull externally exerted on the cord and transmitted therethrough will be intercepted by the push piece. If this device happens to be intended for use with a twin-core cord, it is incapable of retaining a coaxial cord or any other cord having a circular cross section. In the latter cord retaining device, two halved blocks thereof are provided with matching grooves which are so shaped as to give a path for admitting a cable when said blocks are folded over each other. Again the path thus formed has a fixed contour which only fits a cord possessing a conforming cross section. Thus, this device is usable only with either a twin-core cord or a circular cord but cannot be used with both types of cord.
Thus, no conventional cord retaining device is capable of retaining various cords of differing cross sections such as twin-core cords and coaxial cords. Thus, the conventional devices have lacked interchangeability.
An object of this invention is to provide a cord retaining device which possesses paths suitable for admitting two kinds of cords having different cross sections from each other and enjoys ready interchangeability.
Another object of this invention is to provide a cord retaining device which can be integrally shaped easily and inexpensively by injection molding of a plastic material.